Burglar-alarm.



W, T. EUELLANDQ BURGLAR ALARM.

APPLICATION FILED Aue ism.

Patented Feb. 26, 1918.

'ATTORNEY WILLIAM 'r. irrnntann, or nests siren-tween, vrasninaroiv.

BURGLAR-ALABM.

specification of Letters Patent.

iF'at-ented Feb. 236, rare.

Application filed August 1, 1917. Serial No. 183,952.

To. all whom it may concern Be it known that I, W'ILLrAM T. Kann- LAND, a citizen of the United States, residing at East Etanwood, in the county of Snohomish and State of \Vashington, have invented new and useful improvements in Burglar-Alarms, of which the following is a specification. 7

This invention is an improved burglar alarm, the object of the invention being to provide a cheap and simple alarm apparatus which is adapted to be attached to a door knob and which is set in operation by even av slight turning of the knob so that it is impossible for a person to even turn the knob of a door provided with the burglaralarm without setting the alarm in opera tion.

Another object of the invention is to provide an improved mechanism oi this kind which is toldable and can be readily carried.

The invention consistsin the construction combination and arrangement of devices hereinafter described and claimed.

in the accompanying drawings Figure 1 is anelevation, partly in section of a burglar alarm constructed and arranged in accordance with my invention, and with a door knob spindle and a key of the lock indicated in dotted lines.

Fig. 2 is a vertical sectional view of the same on the plane indicated by the line 22 of Fig. 1.

Fig. 3is a horizontal sectional. view of the same on the plane indicated by the line 3-3 of Fig. 1.

Fig. l is a detailed vertical sectional View, showing the alarm mechanism and its connections.

Fig. 5 is a similar view showing the link and its connections.

In the embodiment of my invention I provide an attaching member 1 which has a notch 2 in one side adapted to receive the sleeve A of a door knob and provided at the lower side of the notch with a shoe 3 to bear against the under side of the sleeve and provided at the upper side of the notch with a set screw 4 to bear on the spindle so that said attaching member may be readily detachably secured to the sleeve and caused to turn therewith when the knob is turned by a person attempting to enter through the door. The attaching member is here shown as hollow, and. as made of sheet metal and comprising side walls and top and bottom walls. A clamping member 5 is arranged at one side of the attaching member, is pivotally mounted between the side walls of the attaching member as at 6, and is pro vided at its lower end with a spring finger piece 7.

An arm 8 is'pivotally attached at its upper end at 9 to the lower portion of the attacl'iing member and depends therefrom. Said arm. has a slot 10 through which the key 18 ot the door lock extends, the key serving to hold the arm against turning movement and to insure relative angular or piv tal movement between the arm and the attaching member when the latter is turned by the knob.

An alarm mechanism 11 is mounted on thelower portion of the arm and may be of any suitable construction. As here shown the alarm mechanism comprises a bracket or casing 12 secured on the arm 8. The winding shaft 13 is mounted in bearings in said bracket or casing and said arm and has the usual ratchet wheel. 14- and the usual loose spur gear 15. The spur gear is provided with a spring pressed pawl 16 which enthe ratchet wheel. A spring 17 is attached at one end to and is coiled on the winding shaft and has its free end attached to a stud 18 which projects from the arm. It link 19 has a slot :20 through which said stud and the winding shaft extend so that the link is mounted for sliding movement. The spur gear engages a pinion :21 on a shaft 22. Said shaft has an escapement wheel 2. A shaft 2% is provided with an escapement 25 which coacts with the escapement wheel and is also provided with an arm 26 having a hammer 27 to strike a bell 28, said shaft being further provided with a vibrating arm 29. A spring trip 30 which normally engages behind a vibrating arm and holds the escapement in. position to lock the escapement wheel is attached at one end to the bracket or casing 24 and at the opposite end to a trip member 31, said trip member being pivotally mounted on the winding shaft. The link 19 has a stop 32 on one side to engage one end of the trip member, and has a stop 83 on the opposite side to engage under the trip member, near the opposite end of the latter. Hence said trip membar is caused to release the spring trip or detent element from the vibrating arm when downwardly, and thereby start the alarm apparatus in operation. Said link is connected by a rod 35 to the attaching member, said rod having a book 36 at its upper end to engage in an opening in the bottom of the attaching member. T he clamping member 5, when in normal position engages its spring 7 on the upper side of the hook to lock the rod against longitudinal movement with respect to the attaching member. 7

In the event that the knob should be turned in either direction the attaching member turns therewith so that the rod 35 is caused to draw the link 19 in one direction or the other and hence either the stop 32 or the stop 33 of said link moves the free end of the trip member 31, thereby causing the detent spring to disengage the vibrating arm and setting the alarm apparatus in operation. Hence an alarm is sounded in the event of even an attempt to open the door and at the first turning movement of the knob of the door lock.

By first disengaging the clamping member 5 from the book of the rod 35 the latter may be unhooked from the attaching member l and the latter folded inwardly over the arm '8, thus compactly arranging the burglar alarm and enabling the latter to be placed in a pocket or other receptacle.

While I have herein shown and described a preferred form of my invention 1 would have it understood that changes may be made in the form, proportion and construction of the several parts, without departing Copies of this patent may be obtained for from the spirit of my invention and within the scope of the appended claims.

Having thus described my invention, I claim 1. In an alarm mechanism of the class described, a winding shaft, a stud, a vibrating arm, a trip member pivotally mounted on the winding shaft and arranged to engage the vibrating arm, and a link having a longitudinal slot through which the winding shaft and stud extend, so that said link is slidably mounted, said link having stop devices on opposite sides to engage said trip member so that the trip member will be turned and caused to release the vibrating arm when the link is moved in either direction.

2. A burglar alarm of the class described comprising a relatively fixed member, an attaching member having means whereby the same may be secured to a door knob to be turned thereby, an alarm apparatus mounted on one of said members and tripping means for said alarm apparatus, to set the same in operation, and including a connecting member extending to the other member so that relative angular movement of the attaching member and relatively fixed member will cause the alarm apparatus to be set in operation, said attaching member and relatively fixed member being pivotally connected together and fold-able one upon the other.

In testimony whereof I afiix my signature.

W'ILLIAM '1. KJ ELLAN D.

five cents each, by addressing the Commissioner of Patents,

Washington, D, C. 

